Right now, doctors can detect a tumor that’s around a centimeter in diameter — maybe they could get down to five millimeters. We could measure a tumor that’s a millimeter in diameter. If this works, we could be smarter about understanding cancer."

The rub? McCann needs $100,000 to keep his research going, but isn't confident he'll get it because "One of the complicated factors is that I’m not a medical researcher. I have absolutely no credibility with the National Institutes of Health or any other medical funding agency."

The light bulb for a breathalyzer popped up over McCann's head about 15 years ago when he learned dogs showed an ability to detect cancer.

McCann is not alone in his work. Similar innovations have taken place at the University of Florida, where a breathlyzer is being developed that could detect lung cancer, as well as Parkinson's, pneumonia and other lung infections.

The Cleveland Clinic has also joined the fight with a breathalyzer that can diagnose lung cancer.